There are other risks associated with taking unnecessary antibiotics, such as secondary infections and allergic reactions, the researchers said."Patients figure that taking antibiotics cannot hurt, and just might make them improve," said David Broniatowski, assistant professor at the George Washington University in the US.

"More than half of the patients we surveyed already knew that antibiotics do not work against viruses, but they still agreed with taking antibiotics just in case," Broniatowski added.

For the study, the researchers surveyed 113 patients in an urban hospital to test their understanding of antibiotics. They discovered a widespread misconception: Patients may want antibiotics, even if they are aware that drugs will not improve their viral infection. These patients believe that taking the medication will not worsen their condition - and that the risk of taking unnecessary antibiotics does not outweigh the possibility that they may help.

"We need to fight fire with fire. We need to let them know that antibiotics can have some pretty bad side effects, and that they will definitely not help cure a viral infection," Broniatowski said.The study appeared in the journal Medical Decision Making.